package org.example.red_black_tree;

import java.util.ArrayList;

import org.example.set.FileOperation;

/**
 * 红黑树
 * 等价于2-3树
 */
public class RBTree<K extends Comparable<K>, V> {
    private static final boolean RED = true;
    private static final boolean BLACK = false;

    private class Node{
        public K key;
        public V value;
        public Node left, right;
        public boolean color;

        public Node(K key, V value){
            this.key = key;
            this.value = value;
            left = null;
            right = null;
            color = RED;
        }
    }

    private Node root;
    private int size;

    public RBTree(){
        root = null;
        size = 0;
    }

    public int getSize(){
        return size;
    }

    public boolean isEmpty(){
        return size == 0;
    }

    /**
     * 判断节点node的颜色
     * @param node 节点
     * @return 颜色boolean类型
     */
    private boolean isRed(Node node){
        if (node == null) {
            return BLACK;
        }
        return node.color;
    }

    /**
     * 左旋转
     *   node                    x
     *  /   \     左旋转        /  \
     * T1    x   --------->  node   T3
     *      / \              /   \
     *     T2 T3            T1   T2
     * 
     * @param node 节点
     * @return 旋转后的根节点
     */
    private Node leftRotate(Node node){
        Node x = node.right;
        node.right = x.left;
        x.left = node;

        x.color = node.color;
        node.color = RED;

        return x;
    }

    /**
     * 右旋转
     *     node                   x
     *    /   \     右旋转       /  \
     *   x    T2   ------->   y   node
     *  / \                       /  \
     * y  T1                     T1  T2
     * 
     * @param node 节点
     * @return 旋转后的根节点
     */
    private Node rightRotate(Node node){
        Node x = node.left;
        node.left = x.right;
        x.right = node;

        x.color = node.color;
        node.color = RED;

        return x;
    }

    /**
     * 颜色反转
     * @param node 节点
     */
    private void flipColors(Node node){
        node.color = RED;
        node.left.color = BLACK;
        node.right.color = BLACK;
    }

    /**
     * 向二分搜索树中添加新的元素
     * @param key 键
     * @param value 值
     */
    public void add(K key, V value){
        root = add(root, key, value);
        // 最终根节点为黑色节点
        root.color = BLACK;
    }

    /**
     * 向以node为根的二分搜索树中插入元素(key, value)，递归算法
     * 
     * @param node 以node为根
     * @param key 键
     * @param value 值
     * @return 返回插入新节点后二分搜索树的根
     */
    private RBTree<K, V>.Node add(RBTree<K, V>.Node node, K key, V value) {
        if (node == null) {
            size ++ ;
            // 默认插入红色节点
            return new Node(key, value);
        }

        if (key.compareTo(node.key)<0) {
            node.left = add(node.left, key, value);
        }else if (key.compareTo(node.key)>0){
            node.right = add(node.right, key, value);
        }else{ //key.compareTo(node.key)==0
            node.value = value;
        }

        if (isRed(node.right) && !isRed(node.left)) {
            node = leftRotate(node);
        }

        if(isRed(node.left) && isRed(node.left.left)){
            node = rightRotate(node);
        }

        if (isRed(node.left) && isRed(node.right)) {
            flipColors(node);
        }
        return node;
    }

    /**
     * 返回以node为根节点的二分搜索树中，key所在的节点
     * @param node 以node为根节点
     * @param key 键
     * @return key所在的节点
     */
    private Node getNode(Node node, K key){
        if (node == null) {
            return null;
        }
        if (key.equals(node.key)) {
            return node;
        }else if (key.compareTo(node.key)<0){
            return getNode(node.left, key);
        }else{ // key.compareTo(node.key)>0
            return getNode(node.right, key);
        }
    }

    public boolean contains(K key){
        return getNode(root, key)!=null;
    }

    public V get(K key){
        Node node = getNode(root, key);
        return node == null ? null : node.value;
    }

    public void set(K key, V value){
        Node node = getNode(root, key);
        if (node == null) {
            throw new IllegalArgumentException(key + "doesn't exists");
        }
        node.value = value;
    }

    // 返回以node为根的二分搜索树的最小值所在的节点
    private Node minimum(Node node){
        if(node.left == null)
            return node;
        return minimum(node.left);
    }

    // 删除掉以node为根的二分搜索树中的最小节点
    // 返回删除节点后新的二分搜索树的根
    private Node removeMin(Node node){

        if(node.left == null){
            Node rightNode = node.right;
            node.right = null;
            size --;
            return rightNode;
        }

        node.left = removeMin(node.left);
        return node;
    }

    // 从二分搜索树中删除键为key的节点
    public V remove(K key){

        Node node = getNode(root, key);
        if(node != null){
            root = remove(root, key);
            return node.value;
        }
        return null;
    }

    private Node remove(Node node, K key){

        if( node == null )
            return null;

        if( key.compareTo(node.key) < 0 ){
            node.left = remove(node.left , key);
            return node;
        }
        else if(key.compareTo(node.key) > 0 ){
            node.right = remove(node.right, key);
            return node;
        }
        else{   // key.compareTo(node.key) == 0

            // 待删除节点左子树为空的情况
            if(node.left == null){
                Node rightNode = node.right;
                node.right = null;
                size --;
                return rightNode;
            }

            // 待删除节点右子树为空的情况
            if(node.right == null){
                Node leftNode = node.left;
                node.left = null;
                size --;
                return leftNode;
            }

            // 待删除节点左右子树均不为空的情况

            // 找到比待删除节点大的最小节点, 即待删除节点右子树的最小节点
            // 用这个节点顶替待删除节点的位置
            Node successor = minimum(node.right);
            successor.right = removeMin(node.right);
            successor.left = node.left;

            node.left = node.right = null;

            return successor;
        }
    }

    public static void main(String[] args){

        System.out.println("Pride and Prejudice");

        ArrayList<String> words = new ArrayList<>();
        if(FileOperation.readFile("pride-and-prejudice.txt", words)) {
            System.out.println("Total words: " + words.size());

            RBTree<String, Integer> map = new RBTree<>();
            for (String word : words) {
                if (map.contains(word))
                    map.set(word, map.get(word) + 1);
                else
                    map.add(word, 1);
            }

            System.out.println("Total different words: " + map.getSize());
            System.out.println("Frequency of PRIDE: " + map.get("pride"));
            System.out.println("Frequency of PREJUDICE: " + map.get("prejudice"));
        }

        System.out.println();
    }
}
